The goal of this project is to identify and explore the molecular mechanisms of suppression of autoimmunity utilizing CD8+ Ti, CD4+CD25+ T regulatory cells with specific targeted genes differentially expressed by CD8+ inhibitory T cells (Ti) and CD4+ CD25+ T regulatory cells from tolerized mice compared to na[unreadable]ve littermates in our murine model of SLE. Tolerization of young BWF1 mice with an artificial peptide that contains MHC Class I and Class II T cell determinants from Ig induces two sets of regulatory/inhibitory T cells that suppress autoantibody production. Genome scans of the first;pCONS-binding CD4+CD25+ Treg, show large numbers of genes upregulated and down regulated. The second, CD8+CD28- inhibitory T cells suppress autoantibody production in vitro- an effect that depends on secretion of TGF[unreadable]1 and IFN? - and on adoptive transfer prevent disease in vivo. The number of genes upregulated or down regulated in those CD8+ Ti compared to CD8+CD28- T cells from unmanipulated littermates, is small. We chose 4 upregulated genes from CD8+Ti to study their role in suppressive function, which is directed against CD4+CD25- helper T cells. Upregulation of those genes in the CD8+Ti was identified by genome scan, and then confirmed by real-time PCR in multiple experiments. The 4 genes are Ifi202B, Trp53, bcl2 and Foxp3. Each gene is known to play a role in cell apoptosis, and each is influenced by levels of IFN and/or TGF[unreadable]. Our strategy is to silence each of the 4 genes, alone or in combination, in CD8+ Ti, then measure the effect of that silencing on expression of Foxp3 and on cytokine production in the CD8+Ti cell itself and in its CD4+ helper T cell target. We will study the effects of silencing the genes of interest in vivo in adoptive transfer experiments. The overall purpose is to understand the molecular mechanisms by which these CD8+ inhibitory T cells and CD4+ T regulatory cells suppress autoimmunity;results may identify new targets for therapies for SLE in patients.